The review site Steam Queen says a steam mop should not be used on laminate floors. Using a steam mop, over time, causes damage to the flooring that is not covered under the warranty for the flooring or the mop.
Laminate flooring receives its alluring shine from a top coat that is sensitive to heat and moisture. Much like wallpaper, if you continue to apply heat and steam to this top coat, it begins to warp and peel. The damage may be imperceptible at first, but by the time it is noticeable, the damage is permanent. In fact, most laminate flooring manufacturers specifically say that using a steam mop voids a warranty.